This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The outer membrane of Gram-Negative Bacteria is an important permeability barrier that consists of an asymmetric bilayer in which the inner leaflet is primarily composed of phospholipids and the outer leaflet is primarily composed of lipopolysaccharides (LPS). Outer membrane proteins (OMPs) of the ?-barrel family span the bilayer and serve as channels and transporters. Using a chemical genetic approach, we recently identified a multi-protein complex that spans the periplasm that is responsible for the assembly of LPS. We are currently pursuing biochemical and structural studies of these proteins in order to understand how the hydrophobic LPS molecule is transported to and assembled in the outer leaflet of the OM. We hope to identify whether there are general principles that guide the assembly of this membrane and to characterize these new protein targets for antibiotic development.